Since polycarbonate resins are excellent in mechanical strength, electric properties and transparency, they are widely used as engineering plastics in various fields such as electric and electronic equipment and automobiles. As polycarbonate resins having the above characteristic properties, there are known glass-fiber-reinforced polycarbonate resins prepared by adding glass fibers in order to improve mechanical strength and dimensional stability (Patent Document 1). Meanwhile, materials having higher stiffness are now desired as electric and electronic equipment and car goods are becoming smaller in size and lighter in weight. Then, attempts have been made to improve stiffness by increasing the amount of glass fibers but weld strength and flame retardancy are impaired along with an increase in the amount of glass fibers. Therefore, a polycarbonate resin which satisfies all the requirements for stiffness, weld strength and flame retardancy has not been developed yet, and the development of a material having these properties at the same time has been strongly desired.
For example, there is known a resin composition which comprises a polycarbonate resin and glass fibers having a specific cross-sectional shape and has improved flame retardancy (Patent Document 2). However, since this resin composition is not satisfactory in terms of the effect of improving weld strength and flame retardancy, the improvement of these properties is desired.
Various methods for improving mechanical strength and impact resistance both of which are reduced by the addition of glass fibers by introducing a polycarbonate-polyorganosiloxane copolymer into an aromatic polycarbonate resin are now under study (Patent Documents 3 and 4).
A resin composition which comprises an aromatic polycarbonate resin, a polycarbonate-polyorganosiloxane copolymer and glass fibers treated with a specific sizing agent is known (Patent Document 5).
Further, it is proposed to improve weld strength by introducing a polyarylate resin and a compound having a specific functional group into a composition comprising a polyamide resin and glass fibers (Patent Document 6). However, there is not disclosed information which is effective in improving the stiffness, weld strength and flame retardancy of a resin composition.